Let $f(x) = 10x^{2}-4x-10$. Where does this function intersect the x-axis (i.e. what are the roots or zeroes of $f(x)$ )?
Explanation: The function intersects the x-axis when $f(x) = 0$ , so you need to solve the equation: $10x^{2}-4x-10 = 0$ Use the quadratic formula to solve $ax^2 + bx + c = 0$ $x = \dfrac{-b \pm \sqrt{b^2 - 4ac}}{2a}$ $a = 10, b = -4, c = -10$ $ x = \dfrac{+ 4 \pm \sqrt{(-4)^{2} - 4 \cdot 10 \cdot -10}}{2 \cdot 10}$ $ x = \dfrac{4 \pm \sqrt{416}}{20}$ $ x = \dfrac{4 \pm 4\sqrt{26}}{20}$ $x =\dfrac{1 \pm \sqrt{26}}{5}$